JP7106573B2 - Fast-drying ink composition for continuous inkjet application - Google Patents

Description

BACKGROUND In inkjet printing, printing is accomplished without contact between the printing device and the substrate on which the printed characters are deposited. Briefly, inkjet printing involves ejecting a stream of ink droplets onto a surface and controlling, for example, electronically, the direction of the stream such that the droplets form the desired printed image on the surface. This non-contact printing technique is well suited for applying characters to a variety of surfaces, including porous and non-porous surfaces.
In general, inkjet ink compositions should meet certain requirements to facilitate inkjet printing operations. These requirements relate to component viscosity, resistance, solubility, compatibility, and substrate wettability. In addition, the ink should be fast-drying and smear-resistant, should pass through inkjet nozzles without clogging, and allow rapid cleaning of mechanical parts with minimal effort. should be possible. Additionally, the jet ink composition should provide printed images that adhere well to surfaces, particularly non-porous substrates, which pose challenges for achieving image deposition as known to those skilled in the art.

Most continuous inkjet (CIJ) inks use methanol and/or methyl ethyl ketone (MEK) as the solvent or primary solvent. The inks provide fast dry times, good adhesion due to their volatility, and methanol and MEK are good solvents for the binder resin and dyes in the inks. However, both MEK and methanol are on the Japanese ISHL Class 2 Organic Solvent List and cannot exceed 5 mass % in Japan. Therefore, due to the health and safety concerns of MEK and methanol, regulations such as VOCs (volatile organic compounds) and HAPs (hazardous air pollutants), attempts have been made to develop inks based on other solvents. In the US, both MEK and methanol are controlled under VOC regulations. Methanol is regulated as HAP. In Europe, methanol is listed as a toxic chemical and requires a skull and cross-bone symbol on its label. In addition, methanol is on the European Council of Paint, Printing Ink, and Artists' Colors Industry (CEPE) list of exclusions for printing inks and related products. Therefore, it would be preferable to develop an ink product that avoids the use of MEK and methanol.

Besides MEK and methanol, alternative solvents proposed for inkjet ink compositions include acetone, methyl acetate, dioxolane, and ethyl acetate. However, acetone and methyl acetate are too volatile for inkjet printing, leading to lower printer reliability in high temperature environments as well as higher replenishment consumption requirements. Dioxolane and ethyl acetate are less effective at imparting ink conductivity, requiring the addition of more conductive agents, leading to poorer adhesion of the ink composition to the substrate. Additionally, all these solvents still suffer from health, safety, and odor concerns, especially when printing on certain food packaging materials.
1,2-Dimethoxyethane, which is also used in inkjet compositions, is not on the Japan ISHL Class 2 Organic Solvent List, but is actually regulated to protect the health and safety of MEK and workers. poses more health risks than many other solvents. So this is not a good substitute.

Other ink products, such as VIDEOJET® V460, are relatively safe and are based on ethanol, which is not on the Japan ISHL Class 2 Organic Solvent List. Ethanol and n-propanol are more acceptable solvents for inkjet ink compositions. This is because they have a low odor and relatively low toxicity. They are not regulated under HAP and are not included in the CEPE exclusion list. However, ethanol and n-propanol have poor solvency or poor compatibility with many of the resins, dyes, and conductive agents commonly used in MEK-based inkjet inks. . Therefore, the development of ethanol and/or n-propanol inks that meet ink adhesion and ink stability requirements is more difficult due to the limited options available for binder resins, dyes, and conductive agents. In this connection, n-propanol is even more difficult to use than ethanol because n-propanol has a lower dissolving power for binder resins and dyes. Additionally, ethanol inks tend to absorb water, especially in moist environments, causing other problems during use, making printer operation unreliable or requiring an air dryer. Ethanol solvent inks are impractical in certain geographic areas due to humidity. Additionally, some resins suitable for ethanol-based ink compositions, such as phenolic resins, are not considered very safe due to the presence of residual phenol and traces of formaldehyde in ink compositions using phenolic binders. Polyamide resins tend to precipitate out of solution when the ink absorbs water from the environment, which also leads to unreliable printer operation, especially in wet environments. The use of ethanol, either as the sole solvent or even as a minor component of a solvent mixture, also increases ink drying time. Additionally, ethanol-containing inks face difficulties and restrictions on importation into certain countries and regions due to strict import laws on alcohol. Therefore, an ink free of more hazardous organic solvents and free or substantially free of ethanol, but still having adhesion and other properties similar to traditional prior art MEK inks would be advantageous.

Accordingly, there is a need in the art for continuous ink jet ink compositions that meet the requirements of reliable printing and safety to the workers who manufacture and use the compositions, as well as those in food packaging and food manufacturing environments. There is a request regarding the use of

SUMMARY OF THE INVENTION The ink compositions of the present embodiments are suitable for inkjet printing in a variety of ink and printing applications, preferably industrial applications, and are less regulated and safer than traditional solvents used in continuous inkjet printing. use a suitable solvent. These compositions use greater than 60% by weight of volatile C5 ketone solvent and avoid the use of appreciable or substantial amounts of organic solvents listed on the Japan _ISHL Class 2 Organic Solvent List.
Embodiments of the present invention comprise (a) greater than 60% by weight of one or more volatile C5 ketone solvents; ₍ b) one or more binder resins; and (c) one or more colorants, and substantially It relates specifically to ink compositions that do not contain acetone, methanol, or methyl ethyl ketone. In preferred embodiments, the one or more volatile C5 ketone solvents are selected from the group consisting of 2-pentanone, ₃ -pentanone, 3-methyl-2-butanone, and mixtures thereof.
An embodiment of the present invention is an ink composition comprising: (a) one or more volatile C5 ketone solvent present at greater than ₆₀ % by weight of the ink composition; (b) one or more binder resin; and (c) one or more colorants. Preferred embodiments of the present invention include (a), (b), and (c) above, wherein the ink composition contains less than 5% by weight of acetone, methanol, methyl ethyl ketone, or any combination thereof. Additionally, certain preferred embodiments of these ink compositions further contain ethanol, n-propanol, or combinations thereof in amounts up to 30%, or up to 15%, or up to 5%.

Highly preferred ink compositions are substantially free of acetone, methanol, ethanol, or methyl ethyl ketone.
Preferred ink compositions as described above, wherein the one or more volatile C5 ketone solvents are ₂ -pentanone (methyl propyl ketone), 3-pentanone (diethyl ketone), 3-methyl-2-butanone (methyl isopropyl ketone), and mixtures thereof. Most preferred are ink compositions in which the one or more volatile C5 ketone solvent is ₃ -methyl-2-butanone (methyl isopropyl ketone).
Additionally, the ink composition can contain greater than 70 wt% of one or more volatile _C5 ketone solvents or greater than 80 wt% of one or more volatile _C5 ketone solvents.
In the present invention, one or more binder resins are selected from the group consisting of cellulose ester resins, vinyl resins, modified rosin ester resins, polyvinyl butyral resins, polyester resins, and mixtures thereof, and more preferably one or more binder agents. is selected from the group consisting of cellulose ester resins, vinyl resins, polyester resins, and mixtures thereof, most preferably the cellulose ester resin is a cellulose acetate propionate resin. Preferred ink compositions are those in which one or more binder resins are present in an amount of about 5.0% to about 13.0% by weight of the ink composition.

In certain embodiments of the invention, the one or more colorants are selected from the group consisting of Solvent Black 29, Solvent Black 27, and mixtures thereof, preferably the one or more colorants are Solvent Black 29, e.g. ORASOL BLACK X55 ^™ , VALIFAST BLACK® 3808, and DL BLACK N36B ^™ .
In another embodiment of the present invention, the ink composition further comprises one or more additives selected from the group consisting of surfactants, plasticizers, adhesion promoters, conductive agents, defoamers, and mixtures thereof. There is Surfactants are preferably polyalkylene oxide-modified polysiloxanes. Preferably, one or more surfactants are present in an amount of about 0.1% to about 2.0% by weight of the ink composition.
A further embodiment of the present invention is a method of continuous ink inkjet printing on a substrate, comprising: directing a stream of droplets of the above ink composition onto the substrate; drying the droplets; There is a method comprising printing an image on said substrate. The substrate is a porous, semi-porous, or non-porous substrate selected from the group consisting of, for example, uncoated paper, coated paper, rigid or flexible plastics, polymeric films, metals and alloys, glass, and ceramics. obtain.

Detailed description of the preferred embodiment
1. Definition
The use of the terms "a" and "an" and "the" and similar referents in the context of the description of the invention (particularly in the context of the claims below) shall be used unless otherwise specified herein or in the context. should be construed to include both singular and plural unless clearly contradicted by. The terms “comprising,” “having,” “including,” and “containing” are to be interpreted as open-ended terms unless otherwise specified. should (ie mean "including but not limited to"). Recitation of ranges of values herein, unless otherwise specified herein, is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, and each separate The value of is incorporated herein as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. Any and all examples, or exemplary language given herein (eg, "like"), unless otherwise claimed, are merely intended to better clarify the invention and are not limiting on the scope of the invention. does not impose No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.
Unless otherwise defined, all technical and scientific terms used herein are intended to have the same meaning as commonly understood in the technical field to which this invention belongs at the time of filing. Although various methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described below. However, those skilled in the art should understand that the methods and materials used and described are examples and may not be the only ones suitable for use in the present invention.

In addition, since measurements are subject to inherent variability, any temperature, mass, volume, time interval, pH, salinity, molality or molality, range, concentration and any other measurements given herein Any quantity, quantity or numerical expression is also an approximation and not an exact or definitive numerical value, unless expressly stated to the contrary. Thus, approximate or relative terms and terms of degree commonly employed in patent applications, such as: about, approximately, substantially, as appropriate to the present invention and understood by those skilled in the art It is appropriate to describe the various aspects of the invention in terms of, consisting essentially of, including, effective amounts, and the like. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art.
As used herein, the term "inkjet" or "ink jet" refers to a type of printing that produces an image by ejecting small droplets of ink onto a substrate such as paper, plastic, metal, glass, or the like. Point to print. The "continuous ink jet" or "CIJ" method is used, for example, for marking and coding products and packaging. In this method, a pump directs a liquid ink composition from a reservoir toward a nozzle to create a continuous stream of ink droplets, which are subjected to a controlled variable electrostatic field, thereby causing droplets to disperse in response to the varying electrostatic field. is charged such that The charged droplets are deflected to the proper location by passing them through another electrostatic field to print the desired pattern on the substrate, or recycled back to storage for later use.

The phrase "substantially free of" or "substantially no" as used herein in the context of solvents or other ingredients in inventive ink compositions preferably indicates a discernible or readily detectable amount of Refers to the absence of an ingredient from a composition. "Substantially free" means an amount below the detection limit of commonly used detection methods known in the art, or an amount below the maximum amount allowed for the compound by regulation, or less than 5%, preferably May refer to amounts less than 2%, less than 1%, or less than 0.5%. Preferably, this amount is the amount allowed under Japanese, European, and/or US regulations for controlled compounds. For example, for the Japan ISHL Class II Organic Solvent List, the total concentration of all solvents in the list (eg, MEK, methanol, acetone, and ethyl acetate) cannot exceed 5% combined in the ink.

However, with respect to ethanol or n-propanol, if ethanol or n-propanol is present in the invention ink composition, the composition by weight, respectively, should not significantly affect coating performance such as dry time and adhesion. should be present as less than 30% of the composition, more preferably less than 15% by weight of the composition. Most preferably, the ink is free or substantially free of ethanol to avoid difficulties when importing into geographic regions with strict regulations on ethanol.
As used herein, the term "solvent" refers to an ingredient whose primary function is to dissolve and carry the other ingredients of the ink composition.
As used herein, the term "colorant" refers to a dye, pigment, or other substance that imparts color or changes the hue of something else, and can refer to any such substance. Colorants include black dyes as well as other colors.
As used herein, the term "volatility" refers to the tendency of a substance to evaporate and is related to the substance's vapor pressure. A volatile solvent is a solvent that has the ability to evaporate or enter the gas phase.
As used herein, the term "additive" refers to an optional ingredient that may be added to the inventive ink composition.
As used herein, the term "binder resin" refers to a substance that helps the ink composition adhere to the substrate to which it is applied during printing. Binders generally refer to materials that hold other materials together to provide a cohesive or cohesive property.
As used herein, the acronym "MEK" refers to methyl ethyl ketone, also known as butanone. MEK is a colorless organic liquid solvent of the formula _{CH3C (} O) _CH2CH3 . As used herein, the acronym "MPK" refers to methyl propyl ketone, also known as 2-pentanone. MPK is an organic liquid solvent of the _{formula CH3CH2CH2C (} O) _CH3 . As used herein, the acronym "MIPK" refers to methyl isopropyl ketone, also known as 3-methyl-2-butanone. MIPK is an organic liquid solvent of the formula ( _CH3 ) _2CHC (O) _CH3 . As used herein, the acronym "DEK" refers to diethyl ketone, also known as 3-pentanone. DEK is an organic liquid solvent of the _{formula CH3CH2C (} O) _CH2CH3 .

2.Overview
The ink compositions described herein utilize one or more volatile C5 ketone (pentanone) solvents, such as MPK, _MIPK , and DEK, along with one or more binder resins and colorants. The composition may optionally contain other additives such as plasticizers, surfactants, conductive agents, additional solvents, adhesion promoters, and/or antifoam agents.
These ink compositions perform well in terms of deposition and dry times and are useful for applications including single nozzle continuous ink jet printing, but may also be used for multiple nozzle continuous ink jet or binary array printing. . Inventive ink compositions differ from inks used in thermal inkjet (TIJ) printing because they do not contain humectants. TIJ ink compositions usually contain a humectant and are up to 30% humectant. The inventive ink compositions have health and safety profiles superior to inks using other organic solvents such as 1,2 _- dimethoxyethane and methanol or using less than 60% volatile C5 ketone solvents. and has better dry time and performance than inks containing ethanol at concentrations higher than 30% by weight.
Inventive ink compositions can be used in Japan without the need for expensive exhaust extraction systems that are required with typical CIJ inks when certain thresholds of regulated solvents are exceeded, and are subject to the Japanese Restricted Items List. It also has application performance and health/safety advantages over other inks developed to comply with. Ink compositions (CIJ inks) that meet Japan's Order for Enforcement Industrial Safety and Health Act but also have application performance similar to typical MEK-based CIJ inks there is demand.

3. Results
Ink compositions were prepared according to embodiments of the present invention. A commercial ink product was obtained for comparative testing. Inventive products were tested for dry time after printing using a VIDEOJET® CIJ sample rig. The results clearly show that the dry time of the inventive composition is comparable to ink products using MEK as a solvent and superior to ethanol-based inks. See Example 3.
The inks were tested for adhesion in four separate tests after the above printing (see Example 4). In the thumb rub, PINK PEARL® eraser, nail scratch, and tape tests, the invention compositions generally outperformed or competed with the prior art compositions. Thus, the inventive inks were safer to manufacture and use, yet suitable for use for their intended purpose.

4. Embodiments of the Invention
Ink compositions of the present invention may have any suitable viscosity or surface tension. Embodiments of the invention have a viscosity at 25°C in the range of 1 cP to 10 cP, preferably in the range of 2 cP to 6 cP. The ink composition preferably has a viscosity of less than about 10 cP, preferably less than about 6 cP at 25°C.
The ink composition of the present invention preferably has a surface tension of about 20 to about 30 mN/m at 25°C.
The ink composition of the present invention preferably has a resistivity of about 500-2000 ohm-cm, preferably about 900-1500 ohm-cm at 25°C.
Inkjet ink compositions according to embodiments of the present invention are preferably stable at minimum and maximum temperatures, such as between -15°C and 62°C, for at least several weeks (eg, 4-6 weeks).
The ink compositions of the present invention are sufficiently volatile to allow high speed printing, with fast dry times to resist smearing and yield good printed products. The dry time of the jet printed message is preferably less than 10 seconds, more preferably less than about 2 seconds.
Solvents and solvent mixtures used in ink compositions according to embodiments of the present invention are _C5 ketone organic solvents and mixtures thereof. The inventive composition contains at least 60% MPK, MIPK, DEK, or a combination thereof, and is substantially free of solvents listed as Class II organic solvents in ISHA Japan. The solvent or solvent mixture preferably does not contain organic solvents that are unacceptable in Japan, Europe, and/or the United States due to health and safety regulations.

Organic solvents listed as Class II under ISHA Japan include acetone, isobutyl alcohol, isopropyl alcohol, isopentyl alcohol (isoamyl alcohol), diethyl ether, ethylene glycol monoethyl ether (Cellosolve ^TM ), and ethylene glycol monoethyl ether. Acetate (Cellosolve ^TM Acetate), Ethylene Glycol Mono-n-Butyl Ether (Butyl Cellosolve ^TM ), Ethylene Glycol Monomethyl Ether (Metyl Cellosolve ^TM ), o-Dichlorobenzene, Xylene, Cresol, Chlorobenzene, Isobutyl Acetate, Isopropyl Acetate, Isopentyl Acetate (isoamyl acetate), ethyl acetate, n-butyl acetate, n-propyl acetate, n-pentyl acetate (n-amyl acetate), methyl acetate, cyclohexanol, cyclohexanone, N,N-dimethylformamide, tetrahydrofuran, 1,1, 1-trichloroethane (trichloroethylene), toluene, n-hexane, 1-butanol, 2-butanol, methanol, methyl ethyl ketone, methyl cyclohexanol, methyl cyclohexanone, methyl n-butyl ketone, styrene (ethenylbenzene, vinylbenzene), and n- Hexane is mentioned. Class I organic solvents under the same system include chloroform, carbon tetrachloride, 1,2-dichloroethane, 1,2-dichloroethylene, 1,1,2,2-tetrachloroethane, trichlorethylene, and carbon disulfide. Class III organic solvents include gasoline, coal tar naphtha, petroleum ether, petroleum naphtha, petroleum benzene, turpentine oil, and mineral spirits.

Preferred ink composition embodiments of the present invention comprise at least one binder resin, although multiple binder resins can be present. The amount of binder resin in the composition can be determined by one skilled in the art and depends on the selected binder resin(s). The total amount of binder resin can be any suitable amount. For example, the binder resin or combination of binder resins is present in an amount of from about 0.1% to about 30%, preferably from about 2% to about 20%, more preferably from about 4% to about 15% of the inkjet ink composition. obtain. Most preferred compositions contain from about 6% to about 14% binder resin.
Any suitable binder resin can be utilized, including soluble or dispersible binder resins. Preferred binder resins are soluble in the _C5 ketone solvent or solvent mixture in the composition. Therefore, preferably any binder resin contemplated for use in the present invention is soluble in MEK, MIPK, DEK, or mixtures thereof. In certain embodiments, the ink composition includes acrylic resins, polyvinyl butyral resins, ethylcellulose resins, polyurethane resins, modified rosin resins, phenolic resins, modified phenolic resins, polyamides, cellulose ethers, cellulose esters (e.g., cellulose acetate, cellulose acetate butyrate). CAB), and cellulose acetate propionate (CAP)), cellulose nitrate resin, polymaleic anhydride, polyester resin, vinyl chloride/vinyl acetate copolymer (vinyl resin), styrene/methacrylate copolymer, aldehyde resin, polyvinyl alcohol, styrene and One or more binder resins selected from copolymers of allyl alcohol, and polyketone resins, and any combination thereof may be included. The term "acrylic" includes both acrylic and/or alkylacrylic polymers and copolymers of acrylics and/or alkylacrylics with other monomers such as styrene and/or alpha-methylstyrene.

Certain embodiments preferably comprise one or more binder resins selected from cellulose ester resins, vinyl resins, modified rosin ester resins, polyvinyl butyral resins, polyester resins, and any combination thereof. In one embodiment, the ink composition comprises a vinyl resin as a primary binder and a hydrogenated rosin resin, CAP resin, or mixture thereof as a secondary binder.
Examples of acrylic resins include styrene, acrylic monomers such as acrylic acid or methacrylic acid, and optionally alkyl acrylate monomers such as methyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, hydroxy acrylate. Examples include styrene-acrylic resins that can be made by copolymerizing with ethyl, hydroxyethyl methacrylate, and the like. Styrene acrylic resins are commercially available under the trade name JONCRYL®. Examples of JONCRYL® resins include JONCRYL® 555, 586, 678, 680, 682, 683, and 67. A preferred resin, JONCRYL® 682, has a weight average molecular weight of about 1700, an acid number of about 238, a softening temperature of about 105°C, and a glass transition temperature of about 56°C. Examples of commercially available vinyl resins are VINNOL® available from WACKER CHEMIE® AG, and vinyl chloride resin (YMCA resin) available from Suzhou Direction Chemical Co. Ltd. Examples of commercially available polyvinyl butyral resins are PIOLOFORM® BN18 available from WACKER CHEMIE® AG and MOWITAL® LP B16H available from KURARAY® America, Inc. An example of a commercially available CAP resin is cellulose acetate propionate available from EASTMAN® Chemical. Examples of commercially available modified rosin esters are SUPER ESTER ^™ A-75 available from ARAKAWA® Chemical and STAYBELITE® Ester 10 available from PINOVA®.

In preferred embodiments, the ink composition is desirably free or substantially free of aldehydes such as formamide, an undesirable residue frequently found in aldehyde-derived phenolic resins such as novolac and resole resins. The composition does not contain a phenolic resin as a binder. Formaldehyde is toxic and a suspected carcinogen. Aldehyde residues, which are often found in the resins, are also believed to adversely affect the color properties of certain dyes, such as azo dyes. The ink composition preferably contains less than 1% or less than 0.5% of any aldehyde-derived phenolic resin by weight of the ink composition. The ink composition is preferably substantially free of aldehyde-derived phenolic resins.
In another preferred embodiment, the ink composition does not contain polyamide as a binder. Polyamide resins tend to precipitate when the ink composition absorbs water from the environment. The ink composition preferably contains less than 1% or less than 0.5% of any polyamide resin by weight of the ink composition. The ink composition is preferably substantially free of polyamide resin.
In other preferred embodiments, the ink composition does not contain a hydroxyaromatic resin as a binder. The ink composition preferably contains less than 1% or less than 0.5% of any hydroxyaromatic resin by weight of the ink composition. The ink composition is preferably substantially free of hydroxyaromatic resins.
Most preferred binder resins are cellulose acetate propionate (CAP), STAYBELITE® Ester 10, polyvinyl butyral (PVB) resin, Dertophene ^™ , VINNOL® E15/45M, TEGO® AddBond LTH, and It's a combination. The most preferred embodiments contain CAP, Staybellite Ester 10 and VINNOL® E15/45M or contain CAP, Dertophene ^™ and Vinol E15/45M or PVB and TEGO® AddBond Contains LTH.

In any of the invention embodiments, the ink composition contains at least one colorant. The colorant can be present in an amount from about 0.1% to about 12%, preferably from about 1% to about 10%, more preferably from about 2% to about 8% by weight of the inkjet ink composition.
The colorant can be any colorant or combination of colorants suitable for printing applications. Colorants are preferably dyes. Embodiments of the present invention utilize one or more dyes as colorants, which dyes are selected from the group consisting of acid dyes, basic dyes, solvent dyes, disperse dyes, mordant dyes and any combination thereof. . Examples of solvent dyes include naphthol dyes, azo dyes, metal complex dyes, anthraquinone dyes, quinoimine dyes, indigoid dyes, benzoquinone dyes, carbonium dyes, naphthoquinone dyes, naphthalimide dyes, phthalocyanine dyes, and perylene dyes.
For example, an ink composition according to certain embodiments of the present invention may include CI Solvent Black 3, CI Solvent Black 5, CI Solvent Black 7, CI Solvent Black 22, Solvent Black 26, CI Solvent Black 27 (e.g. VALIFAST BLACK®). 3840L), CI Solvent Black 29 (e.g. VALIFAST BLACK® 3808, ORASOL BLACK X55 ^™ , and DL BLACK N36B ^™ ), CI Solvent Black 48, and any combination thereof. can include Preferred solvent dyes are Solvent Black 27 (VALIFAST BLACK® 3840L), Solvent Black 29 (ORASOL BLACK X55 ^™ ), Solvent Black 29 (VALIFAST BLACK® 3808) and Solvent Black 29 (DL BLACK N36B ^™ ). is.

The ink compositions of the present invention may further comprise one or more additives such as plasticizers, surfactants, defoamers, adhesion promoters, and mixtures thereof. The additive is preferably miscible with the ink composition and does not phase separate from the composition during application of the ink to the substrate during printing.
An example of a suitable plasticizer for use in embodiments of the present invention is PLASTICIZER #8® available from RIT-CHEM® Co., Inc. The plasticizer additive can be present in an amount from about 0.1% to about 5%, preferably from about 0.3% to about 3% by weight of the inkjet ink composition.
Examples of usable surfactants include fluorosurfactants, siloxanes, silicones, silanols, polyoxyalkyleneamines, propoxylated (poly(oxypropylene)) diamines, alkyletheramines, nonylphenol ethoxylates, ethoxylated Fatty amines, quaternized copolymers of vinylpyrrolidone and dimethylaminoethyl methacrylate, fluorinated organic acid diethanolamine salts, alkoxylated ethylenediamines, polyethylene oxides, polyoxyalkylenepolyalkylenepolyamineamines, polyoxyalkylenepolyalkylenepolyimines, alkyl phosphates. Ethoxylate mixtures, polyoxyalkylene derivatives of propylene glycol, and polyoxyethylated fatty alcohols, or any combination thereof. A preferred example of a suitable polymeric surfactant is the silicone surfactant SILWET® L7622 available from GENERAL ELECTRIC®. The surfactant additive can be present in an amount of about 0.01 to about 1.0%, preferably about 0.02 to about 0.5% by weight of the inkjet ink composition.

The ink composition may also contain an adhesion promoter. Suitable adhesion promoters are silanes such as SILQUEST® WETLINK 78, which is glycidoxypropyldiethoxymethylsilane, SILQUEST® A, which is β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. -186 SILANE, and SILQUEST® A-187 SILANE, which is gamma-glycidoxypropyltrimethoxysilane, all of which are available from GENERAL ELECTRIC®. The adhesion promoter can be present at about 0.1 to about 2%, preferably about 0.2 to about 1.0%, more preferably about 0.5% by weight of the ink composition.
The ink composition preferably contains little or no water. Water is preferably present in an amount of less than 5%, more preferably less than 4%, more preferably less than 2%, and most preferably less than 1% by weight of the inkjet ink composition. The ink composition may contain several other organic solvents, such as ethanol and 1-propanol, which are not listed on the Japan ISHA Class II Organic Solvent List. In particular, when the composition contains one or more organic solvents listed in the Japanese ISHA Class II Organic Solvent List, other organic solvents are preferably less than 5% or less than 1% by weight of the ink composition. is present in an amount of less than 0.5%, more preferably less than 0.1%, more preferably less than 0.01% and most preferably less than 0.001%. For solvents other than volatile C5 ketone solvents (MPK, _MIPK , DEK) not listed on the Japanese ISHA Class II Organic Solvent List, the solvent is less than 30%, preferably less than 15%, more preferably less than 5% less than and most preferably no or substantially no ethanol. Preferred ink compositions may contain other organic solvents in amounts less than permitted under Japanese, European, or US health and safety regulations. Most preferably, the ink composition does not contain detectable organic solvents such as methanol, MEK, or other solvents listed on the Japan ISHA Class II list, or ethanol.
Additionally, solvents listed as potential drug precursors by the United States Drug Enforcement Agency are not preferred. For this reason, for example, the ink composition should be substantially free of MEK and acetone.

The ink composition of the invention can be prepared by any suitable method. For example, the selected components can be combined and mixed with good agitation and the resulting fluid filtered to remove any undissolved impurities.
The present invention is a method of printing an image on a substrate in a continuous ink jet printer, comprising directing a stream of droplets of any of the embodiments of the inventive ink compositions described herein onto said substrate, Further provided is a method comprising drying the droplets thereby printing an image on said substrate. Any continuous ink jet printing method and equipment known in the art are contemplated for use in the present invention. Any suitable substrate can be printed according to the present invention. Examples of suitable substrates include porous substrates such as uncoated paper and cardboard; semi-porous substrates such as water-coated paper, clay-coated paper, silica-coated paper, UV-overcoated paper, polymer-overcoated paper, and varnish overcoated paper, etc.; and non-porous substrates such as plastics (e.g., high density polyethylene, low density polyethylene), polymer films, etc., metals and alloys (e.g., steel, aluminum, brass, etc.); glass, and ceramics. be done. The paper substrate can be a thin sheet of paper, a roll of paper, or cardboard. Plastic, metal, glass, and ceramic substrates may be in any form, such as bottles or containers, plates, rods, cylinders, and the like. The paper substrate can be an article made of paper or cardboard, including thin sheets of paper, rolls of paper, or sheets of cardboard. In certain embodiments, printing operations can be performed in industries such as the dairy industry, where wet surface penetration may be required during printing.
Due to natural variations in the viscosity of ink compositions made according to the same or similar formulations, the product may be intentionally slightly more concentrated or made at a slightly higher viscosity than required during manufacture of the ink. be done. The product can then be diluted with more or less additional solvent as needed to meet specific viscosity range requirements.

5. Examples
This invention should not be understood to be limited to the particular exemplary processes, compositions, or methodologies described, as such may vary. It is also to be understood that the terminology used in the description is for the purpose of describing particular versions or embodiments only and is not intended to limit the scope of the invention, which is limited only by the appended claims. . Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the embodiments of the present invention, certain specific and preferred embodiments are described herein. All publications mentioned herein are hereby incorporated by reference in their entirety. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such disclosure by virtue of prior invention.

Example 1. Continuous ink jet printing composition.
The following ink compositions 1, 2, 3, 4, 5, 6, and 7 were prepared using the following components.

Example 2. A preferred continuous ink jet ink composition.
The following examples of ink compositions (1, 2, 3, and 7) are preferred. Composition 2 had excellent drying time. See Example 3. Compositions 1, 3, and 7 had favorable adhesion properties. See Example 4.

Example 3. Ink drying time.
The ink compositions described in Table 1 below were tested for dry time on the indicated substrates as follows. A 5×7 matrix alphanumeric code was ink printed onto the substrate using a VIDEOJET® CIJ sample rig (XL sample marker). Immediately after printing, the code was examined by lightly rubbing it with a finger (no smudging) until it was dry. Drying time was measured using a stopwatch. The average of the three dry times was recorded as the ink dry time for a particular substrate, rounded up to 0.5 second increments.
Comparative Example 1 (C1) in Table 1 below is a commercial VIDEOJET® ink product using methyl ethyl ketone (MEK) as the solvent. Comparative Example 2 (C2) in the table below is a commercially available MEK-free continuous inkjet ink product that does not contain organic solvents listed in the Japanese ISHL Class 2 Organic Solvent List, and uses 1,2-dimethoxyethane as the solvent. ing. Comparative Example 3 (C3) in the table below is an ethanol-based product from VIDEOJET®. The remaining numbers refer to the ink composition of Example 1. HDPE = high density polyethylene; LDPE = low density polyethylene; PET = polyethylene terephthalate; PP = polypropylene; PVC = polyvinyl chloride.

Table 1. Ink drying time comparison.

Example 4. Adhesion test.
The ink compositions were tested for adhesion to the printed surface using four separate tests, as shown in Tables 2, 3, 4, and 5 below. These methods were as follows.
For thumb rub adhesion testing, a Videojet CIJ sample rig (XL 101 sample marker) was used to print a 5×7 matrix of alphanumeric code onto the substrate. The test was performed after the printed image was allowed to set for 1 minute. This time the printed code was rubbed (up to 10 times) with a clean thumb across the cord in one direction with moderate pressure, trying to cover exactly the same area of the cord for every rub. The number of rubs required to change or remove the image was recorded and assigned a numerical value on a scale of 1-6 based on that. See the grading scale listed below Table 2.

For the PINK PEARL® eraser test, the fingernail scratch test, and the tape test, the printed image was allowed to set for 24 hours before testing. In the PINK PEARL® Eraser test, the printed substrate is placed face up with the printed code on a rigid surface and the PINK PEARL® Eraser is applied from left to right across the printed characters with approximately 3 kg of force. rubbed with A balance was used to calibrate the force as needed. The number of erasers required to alter or remove the image was recorded and then based on the number of erasers assigned a numerical value on a scale of 1-6 using the rating scale described below in Table 3.
In the fingernail scratch test, the printed substrate is placed face up on a hard surface with the printed code and the code is rubbed exactly the same for every scratch using a thumb nail from left to right along the code with moderate pressure. Scratched while trying to cover the area. The number of scratches required to change or remove the image was recorded and then based on the number of scratches assigned a numerical value on a scale of 1-6 using the grading scale described below in Table 4.
In the tape test, the printed substrate is placed face up with the printed code on a rigid surface and a tape (3M SCOTCH® Transparent Tape #600 or equivalent) is applied to ensure full contact with the printed surface. To do this, one firm (3 kg) rub was used to flatten the tape surface and apply it over the entire printed code. The tape was then removed by grasping the free end and pulling it toward itself (not rattling) as quickly as possible at an angle as close to 180° as possible. Cords and tapes were evaluated and compared to untested cords. A rating scale of 1 to 6 was assigned based on the visibility of the code and the amount of ink transferred to the tape using the grading scale set forth in Table 5 below.
All test prints were made using a VIDEOJET® CIJ sample rig (XL 101 sample marker). Thumb rub adhesion tests were performed 1 minute after printing; the remaining tests were performed 24 hours after printing.

格付け尺度：6＝10×(×＝擦り回数)後に印刷コードに変化なし；5＝10×後に印刷コードのフェーディング(＜50%)、全ての文字が判読可能；4＝10×後に印刷コードのフェーディング(＞50%)、全ての文字が判読可能；3＝10×後に一部又は全ての文字が判読不能だが、5×後には判読可能；2＝5×後に一部又は全ての文字が判読不能だが、1×後には判読可能；1＝1×後に一部又は全ての文字が判読不能。 Table 2. Thumb Rub Adhesion Test.

Rating scale: 6 = no change in printed code after 10x (x = number of rubs); 5 = faded (<50%) in printed code after 10x, all characters legible; 4 = printed code after 10x. fading (>50%), all characters legible; 3 = 10 x some or all letters illegible after 5 x but still legible after 2 = 5 x some or all letters after is illegible, but is readable after 1×; 1=some or all characters are illegible after 1×.

格付け尺度：6＝10×(×＝擦り回数)後に印刷コードに変化なし；5＝10×後に印刷コードのフェーディング(＜50%)、全ての文字が判読可能；4＝10×後に印刷コードのフェーディング(＞50%)、全ての文字が判読可能；3＝10×後に一部又は全ての文字が判読不能だが、5×後には判読可能；2＝5×後に一部又は全ての文字が判読不能だが、1×後には判読可能；1＝1×後に一部又は全ての文字が判読不能。 Table 3. PINK PEARL® Eraser Test.

Rating scale: 6 = no change in printed code after 10x (x = number of rubs); 5 = faded (<50%) in printed code after 10x, all characters legible; 4 = printed code after 10x. fading (>50%), all characters legible; 3 = 10 x some or all letters illegible after 5 x but still legible after 2 = 5 x some or all letters after is illegible, but is readable after 1×; 1=some or all characters are illegible after 1×.

格付け尺度：6＝10×(×＝擦り回数)後に印刷コードに変化なし；5＝10×後に印刷コードのフェーディング(＜50%)、全ての文字が判読可能；4＝10×後に印刷コードのフェーディング(＞50%)、全ての文字が判読可能；3＝10×後に一部又は全ての文字が判読不能だが、5×後には判読可能；2＝5×後に一部又は全ての文字が判読不能だが、1×後には判読可能；1＝1×後に一部又は全ての文字が判読不能。 Table 4. Fingernail scratch test

Rating scale: 6 = no change in printed code after 10x (x = number of rubs); 5 = faded (<50%) in printed code after 10x, all characters legible; 4 = printed code after 10x. fading (>50%), all characters legible; 3 = 10 x some or all letters illegible after 5 x but still legible after 2 = 5 x some or all letters after is illegible, but is readable after 1×; 1=some or all characters are illegible after 1×.

格付け尺度：6＝テープへの移行なし及び印刷コードに可視変化なし；5＝未試験印刷コードと比較したときに初めて区別可能な無視できるテープへの移行；4＝テープへの最小の移行があるが(11～25%)、印刷コードの全ての文字が判読可能；3＝テープへの顕著な移行があるが(26～50%)、印刷コードの全ての文字が判読可能；2＝テープへの顕著な移行(50～99%)；1＝テープへの完全な移行。 Table 5. Tape test.

Rating scale: 6 = no transfer to tape and no visible change in printed code; 5 = negligible transfer to tape distinguishable only when compared to untested printed code; 4 = minimal transfer to tape. (11-25%), but all characters in printed code are legible; 3 = significant transition to tape (26-50%), but all characters in printed code are legible; 2 = to tape significant migration (50-99%); 1 = complete migration to tape.

Example 5. Preferred ink formulation.
The following inks are preferred compositions. Dry time and adhesion tests were performed as described above on the indicator substrates and rated as described above for each test. The results are contained in Table 6 below.

Table 6. Test results.

REFERENCES The references listed below and throughout this specification are hereby incorporated by reference in their entireties.
1. U.S. Patent No. 8,142,559.
2. U.S. Patent No. 8,414,695.
3. U.S. Patent No. 8,632,630.
4. U.S. Patent No. 9,249,326.

Claims (15)

A continuous inkjet ink composition comprising:
(a) a solvent comprising one or more volatile C5 ketone solvents present at greater than ₆₀ % by weight of said ink composition;
(b) one or more binder resins; and
(c) one or more coloring agents;
including
Said ink composition (except for ink compositions containing non-cyclic acetals) may additionally contain ethanol, n-propanol, or a combination thereof in an amount up to 15 % by weight of said ink composition. 2. The continuous inkjet ink composition of claim 1, containing less than 5% by weight of acetone, methanol, methyl ethyl ketone, or any combination thereof. 2. The continuous inkjet ink composition of claim 1, substantially free of acetone, methanol, ethanol, or methyl ethyl ketone. wherein said one or more volatile C5 ketone solvents are from the group consisting of ₂ -pentanone (methyl propyl ketone), 3-pentanone (diethyl ketone), 3-methyl-2-butanone (methyl isopropyl ketone), and mixtures thereof The continuous ink jet ink composition of claim 1, selected. 2. The continuous inkjet ink composition of claim 1, wherein the one or more volatile C5 ketone solvent is ₃ -methyl-2-butanone (methyl isopropyl ketone). 2. The continuous inkjet ink composition of claim ₁ , containing greater than 70% by weight of one or more volatile C5 ketone solvents. 2. The continuous inkjet ink composition of claim ₁ , containing greater than 80% by weight of one or more volatile C5 ketone solvents. The continuous inkjet ink composition of claim 1, wherein the one or more binder resins are selected from the group consisting of cellulose ester resins, vinyl resins, modified rosin ester resins, polyvinyl butyral resins, polyester resins, and mixtures thereof. thing. 2. The continuous inkjet ink composition of claim 1, wherein the one or more binder resins are selected from the group consisting of cellulose ester resins, modified rosin ester resins, polyvinyl butyral resins, and mixtures thereof. 9. The continuous inkjet ink composition of claim 8, wherein the cellulose ester resin is a cellulose acetate propionate resin. The continuous inkjet ink composition of claim 1, wherein said one or more binder resins are present in an amount of 5.0 % to 13.0% by weight of said ink composition. 2. The continuous inkjet ink composition of claim 1, wherein the one or more colorants are selected from the group consisting of Solvent Black 29, Solvent Black 27, and mixtures thereof. one or more surfactants, one or more plasticizers, one or more adhesion promoters, one or more conductive agents, in an amount of 0.1% to 2.0% by weight of the ink composition; The claim further comprising one or more additives selected from the group consisting of one or more antifoam agents, and mixtures thereof, wherein the one or more surfactants may be polyalkylene oxide modified polysiloxanes. 2. The ink composition for continuous inkjet according to 1. A method of continuous ink jet printing on a substrate comprising directing a stream of droplets of the continuous ink jet ink composition of claim 1 onto said substrate and drying said droplets to print an image on said substrate. The above method, comprising: 15. The method of claim 14, wherein the substrate is selected from the group consisting of uncoated paper, coated paper, rigid or flexible plastics, polymeric films, metals and alloys, glass, and ceramics.